A base transceiver station (BTS) apparatus for licensed-assisted access (LAA) to an unlicensed spectrum, for example, a “Distributed Antenna System Supporting Multiband” disclosed in Korean Patent Registration No. 10-1463239 (registered on Nov. 12, 2014), may interface with a BTS for LAA, and transmit a service signal to user equipment (UE) in a shadow zone in one direction and transmit an LAA signal of the UE to the BTS in an opposite direction, thereby enabling an LAA service for an unlicensed spectrum, or an unlicensed band frequency aggregation service.
LAA is a technology needed to meet a growing market demand for high-speed data communications for mobile communication systems. However, not all existing BTS apparatuses interfacing with a BTS support LAA to an unlicensed spectrum, and thus such a lack of support limits the provision of an LAA service.
Accordingly, a BTS apparatus that supports LAA to an unlicensed spectrum is needed to improve the situation described above.